Ridge on mesh after curve modifier
More vertices are most definitely not "better" topology. I'd recommend this blog about the topology topic.

In your case it would be best to start from scratch. If you want to use what you have got, you only need to keep the outline.


Select the outer edge loop with Alt rightclick and ShiftAlt right click.
Invert the selection. CtrlI
Delete all selected vertices. X > Vertices

Then, convert your mesh to a curve with AltC > Mesh to Curve.
Set the curve to 2D and use its extrude features to give the flat surface depth.